The invention relates to base station control in a telecommunications system, such as GSM (Global System for Mobile Communication).
FIG. 1 shows a simplified block diagram of the GSM system. A mobile station MS is connected over a radio path to a base transceiver station BTS, in FIG. 1 to base station BTS1. The mobile station MS receives transmission of a selected base station. A base station subsystem BSS comprises a base station controller BSC, and base transceiver stations BTS1 and BTS2 subordinated thereto, which base transceiver stations further comprise one or more transceivers TRX which can operate on different frequency ranges. Operation of the whole system is controlled by an operation and maintenance centre OMC. The tasks of the base station controller BSC include, for example, channel monitoring and management, frequency hopping control, base station power control and handover control. In general, a plurality of base station controllers BSC are subordinated to a mobile services switching centre MSC.
With the development of mobile systems, new system versions will be created, such as EDGE (Enhanced Data Rates for GSM Evolution) of the GSM and new frequency ranges will also be introduced, such as EGSM 900 (Extended GSM 900 Frequency Band) of the GSM, and GSM 1800. Base stations can be controlled by means of a network object model, in which each base station is modelled by one or more base station objects. The network object model refers to an object model which represents the elements of the radio network. The network object model can be implemented by means of computer software. Within this application the term base station refers to a physical entity and the term base station object refers to an object representing a base station or a part thereof in a network object model. In other words the term base station object means a representation of a base station or a part thereof for control purposes. The controlling entity, such as a base station controller, sees and handles a base station as one or several base station objects. Different systems and different frequency ranges may overlap in the same geographical area. One base station object can generally comprise only transceivers that are mutually of the same type and/or operate on one frequency range, whereby each frequency range requires a separate base station object, for instance.
FIG. 3 illustrates a radio network object model for controlling the base transceiver stations BTS1, BTS2 and BTS3. In the figure each base transceiver station BTS1-3 is represented by one base station object BTSO1, BTSO2 and BTSO3. However, one base station BTS can be represented by means of a plurality of base station objects BTSO. The base station BTS1 comprises two transceivers 3 and 4, which operate on the conventional GSM 900 frequency range (PGSM 900, Primary GSM 900), the base station BTS2 comprises one transceiver 5 operating on the EGSM 900 frequency range and the base station BTS3 comprises one transceiver 6 operating on the GSM 1800 frequency range. Each of the base stations BTS1-BTS3 have their own BCCH channel (Broadcast Control Channel) as shown.
In accordance with the prior art, each base station object controlled by the base station controller BSC is controlled separately. This creates a problem that the number of objects to be administered increases when the number of base station objects of different types and/or operating on different frequency ranges increases.